Pleated filter media can be used for producing conical filters by being applied around end pieces having different diameters and by affixing the two free sides of end pleats to each other along the length thereof. When the length of the filter, the length direction being the axial direction of such a conical filter, reaches a certain length the pleats in the filter medium must be stabilised. One way of accomplishing such a stabilising is to glue one or more continuous cords around the periphery of the applied filter medium. The stabilising of the pleats thus requires a separate process step being made after the applying of the filter medium to the end pieces.
The objective of the present invention is a pleated filter medium which can be applied to end pieces to form a conical filter without the need for a separate stabilising step after forming of the conical filter.